Set-top boxes and digital satellite receivers are widely used for reception of digital television cable programs or satellite programs and operate usually with a smart card to allow also a decoding of scrambled pay television channels. Smart cards, also known as IC cards, are portable information media, having the size of about a credit card. In this description, the expression set-top box will be used for describing an appliance for receiving digital and/or analogue television programs via cable, satellite, or via terrestrial reception.
Set-top boxes are complex digital appliances, which need extensive testing during production and also occasionally servicing after sales due to its highly integrated digital architecture. It is known to provide a digital set-top box with a so-called FFT interface for allowing factory functional tests (FFT). This is a tool, which gives the capability to drive the set-top box hardware through its low level drivers by using an external computer, for example a PC. The computer is coupled via a standard RS232 serial connection to the set-top box, which comprises a respective port for example on the rear panel. This tool allows easy access during the factory process, especially for the consumer test after production of the appliance, when the box is closed. It is also very useful for after sales diagnostics or development tests too.
The size of the set-top boxes is shrinking more and more as the level of integration in the integrated circuits increases. But especially so-called SCART connectors, being used widely in Europe, consume a considerable amount on the rear panel, and the smaller the set-top boxes are, the fewer places are available for connectors. For the basic operations of a set-top box at least video and audio connectors have to be provided, with an audio reproduction usually in stereo, and respective connectors have to be provided on the rear panel of the set-top box, either in the form of individual connectors, in a unique connector having several pins each one dedicated to a specific signal, or in a combination of individual and mixed connectors.
In the earlier European application 022918329.0 a method for testing of an appliance is disclosed, which uses a test adapter being introduced into a smart card reader of the appliance for testing of the appliance. This allows to avoid the RS232 interface, but it is not possible to test the normal operation of the appliance with a smart card, when using this test procedure. For the testing of all functions of a set-top box, the computer link must not be exclusive with any other standard function being provided by the set-top box.